Combined etching and doping substances

Abstract

The invention concerns etching and doping substances free of hydrochloric/fluoride acid used for etching inorganic layers as well as for doping subjacent layers. The invention also concerns a method wherein said substances are used.

1. A combination comprising
 an inorganic passivation or anti-reflection layer on a solar cell and 
 an etching and doping medium for the etching and doping of an inorganic passivation or anti-reflection layer on a solar cell, consisting essentially of a paste having as active component, ortho-, meta- or pyrophosphoric acid, and/or meta-phosphorus pentoxide or a mixture thereof, wherein said paste acts both as etching component and as doping component. 
 
     
     
       2. A combination according to  claim 1 , comprising one or more ammonium salt(s) of phosphoric acid and/or mono- or diesters of a phosphoric acid, which liberate the etching phosphoric acid through thermal input of energy. 
     
     
       3. A combination according to  claim 1 , further comprising solvents, thickeners and optionally additives, such as antifoams, thixotropy agents, flow-control agents, deaerators and adhesion promoters. 
     
     
       4. A method for the n ++  doping of silicon comprising applying an etching and doping paste according to  claim 1  to an inorganic passivation and anti-reflection layer on a solar cell. 
     
     
       5. A method for the production of a solar cell with two-stage emitters comprising applying an etching and doping paste according to  claim 1  to an inorganic passivation and anti-reflection layer on a solar cell. 
     
     
       6. A method of etching an inorganic passivation and anti-reflection layer on a solar cell comprising applying the etching and doping paste medium of  claim 1  in a single step process. 
     
     
       7. A combination according to  claim 1 , wherein said active component is present in a concentration range of about 1-80% by weight, based on the total weight of the etching paste. 
     
     
       8. A combination according to  claim 1 , further comprising a nitric acid or a nitrate. 
     
     
       9. A combination according to  claim 3 , wherein said solvent is about 20-80% by weight, based on the total weight of the etching paste. 
     
     
       10. A combination according to  claim 9 , wherein said solvent is water, a monohydric and/or polyhydric alcohol, ethylene glycol monobutyl ether, triethylene glycol monomethyl ether or [2,2-butoxy(ethoxy)] ethyl acetate. 
     
     
       11. An etching and doping medium for the etching and doping of an inorganic passivation or anti-reflection layer on a solar cell, consisting essentially of a paste having as active component, ortho-, meta- or pyrophosphoric acid, and/or meta-phosphorus pentoxide or a mixture thereof, wherein said paste acts both as etching component and as doping component. 
     
     
       12. An etching and doping medium according to  claim 11 , wherein said passivation and anti-reflection layer consists essentially of silicon nitride. 
     
     
       13. An etching and doping medium according to  claim 11 , wherein said paste acts both as sole etching component and as sole doping component.